1.3.2 Pre 10 - CPU Usage

[rconn2]

1. Using the default earth surface, and all rendering options off except planets, and Time static (i.e. frozen or by pressing 'K'). Home in on earth (i.e. Egypt) while watching CPU usage in Task Manager. Around 8,000 km, CPU usage jumps from around 20 to the upper 90's. Move in closer, to around 6,000 km distance, and CPU usage drops back to around 20.

-- Repeat the above using Alt surfaces such as Blue Marble. Same effect.
-- Repeat the above using different Ctrl-V settings, similar effect (not sure but where the jump occurs may differ).

2. With Time static, change rendering options to Nightside and cpu usage jumps to the 90's from the 20's or 30's. Turn off Nightside, and change to Clouds, and the same effect. Move closer or further away from earth and cpu usage stays very high with Nightside or Clouds.

-- When Time is static, the image in Celestia is constant, and no calculations need to be performed. Yet there is no change in cpu usage whether static or time is moving etc. So, just having Nightside or Clouds on, cpu usage stays in the upper 90's, turning on the system fan etc. there's no way to let Celestia idle without closing it down.

[BTW Chris -- Thanks for your great program and generous efforts.]

[maxim]

The display is still updated every 1/40 second (or so). That's what causes the CPU load - calculations have a quite minor effect on it.

BTW - my poor computers CPU load is always at 100%.

maxim

[rconn2]

maxim: Thanks. It'd be much better if the updates could be stopped when time is frozen, so you could just idle Celestia. For example, often I'll stop time and just zoom in, stop, zoom in to study a texture. And, I'll often want to switch to something else for a while.

I'm a relatively new user -- a few weeks now. A great program, but this is a real negative I hope is addressed. I've found myself constantly exiting Celestia after a few minutes because of the constant cpu usage. If I could just spacebar or K to stop, then I wouldn't feel that need. And, I wouldn't want to leave it up and go out for a while -- running the cpu so hot. So, BIG ISSUE I think.

Otherwise, my point #2 still seems an anomoly -- where cpu usage jumps at a certain distance (~8km or so) from earth. It's low, low, med hi, hi, hi, low, low ... just jumps in that distance window.

-- rc

[selden]

rc,

If Celestia can complete all of its calculations and refresh the screen in less time than your screen's refresh rate, then its CPU usage falls off. If Celestia takes longer than your setting for the system's screen refresh rate, then it'll use all of the CPU trying to refresh the screen as fast as it can. It's a very abrupt step-function.

I agree that it'd be nice if Celestia would stop refreshing the screen when it's supposed to be paused.

Celestia does completely stop while one of its drop-down menus is open and you haven't yet selected a menu item. Of course, that also prevents your system's screen-saver from running,
so you have to worry about long-term screen burn-in.

[rconn2]

Selden: Thx. I see bringing up a menu does stop cpu usage... at least a quick trick (but then you can't zoom in etc.).

I just noticed something else though: When you minimize Celestia, cpu usage shoots up to 99%. Just start it up using the default "normal" earth texture... in task manager, I get around 25% cpu. Then minimize, and the cpu gets maxed-out. Ok... just tried with Sol (and everything off except planets) and Pluto... minimize and maxed out cpu!

I'm not being complaining critical (am a developer myself), just pointing out what I believe is a serious flaw -- screen refreshes and high cpu usage shouldn't occur either when time is stopped nor when the program is minimized.

I know I've minimized over the past weeks -- surfing the web, playing w/ cygwin... and had Celestia minimized and noticed my system being sluggish... but figured it was all the stuff I was installing etc. Now I know. I hope this gets addressed; it makes one only want to use only for brief periods when you don't want to do anything else (which is rare).

-- rc

[chris]

I checked a fix into CVS which keeps Celestia from using all available CPU time when it's minimized. Detecting a paused state is more complicated. Just because time is paused doesn't mean that the camera isn't moving. And, with multiview, there's more than one camera to check. It's not really that difficult to determine if the scene needs to be rerendered, but I'm reluctant to add the code to do it so close to 1.3.2.

--Chris

[rconn2]

Chris: Thanks, that sounds great! I understand about the rendering changes and not wanting to impact the impending release of 1.3.2... will look forward to this in another release.

BTW, I've seen a lot of shareware and open source... and Celestia is among the best software, including commercial, I've encountered. I just did a google some weeks ago for astronomy sw, and was happily surprised to come across your gem.

[selden]

fwiw, I just finished downloading a fresh copy of all of the Celestia source code and compiled it on a WinXP Pro SP1 system using MS Visual Studio .NET 2003, and the new "don't compute while minimized" code seems to be working fine!

[symaski62]

win XP sp1


d?marrer => windows update (entr)

/symaski62

[don]

Chris,

Works great!

My 3.06 GHz CPU, 4" ducted fan, my sensitive ears, and my sanity ALL say THANK YOU!